/*
    This file is part of the substandard lisp implementation of Standard Lisp
    Copyright (C) 2011 Nicky Nickell

    substandard lisp is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

(de subst (u v w)
  (cond
    ((null w) NIL)
    ((equal v w) u)
    ((atom w) w)
    (T (cons (subst u v (car w)) (subst u v (cdr w))))))

/*---
name: subst

doc: |
  explaining what subst is / how it is used!

tests: |
  (subst 'a 'b '(a b c)) -> (a a c)
  (subst 1 2 '(1 2 2 2)) -> (1 1 1 1)
  (subst "foo" "bar" '("foo" "bar")) -> ("foo" "foo")
...*/
